Processes for forming dental restorations currently used involve various techniques. One of two common techniques is a lost wax process, and the other is computer modeling and milling.
Initially, as used in this document the terms set forth below have the following meanings:                The term “tooth” may refer to one or more teeth. Similarly, the term “tooth preparation area” may refer to a single tooth which has been prepared for the receipt of a dental restoration, or to several teeth, as well as to the surrounding area.        The term “dental restoration” will apply to inlays, onlays, veneers, crowns, and bridges. In addition, it may also apply to copings.        The term “stone model” as used in this specification refers to a model of the tooth preparation area cast from an impression. The “stone model” may be made from a specially calcined gypsum derivative similar to plaster of paris, but which is stronger than plaster of paris.        The term “computer” may apply to one or more computers.        
The lost wax technique, while providing a very good dental restoration, is both time consuming and requires skilled craftsmen to produce an acceptable product. One of these lost wax processes utilizes IPS Empress® kits which produce a very high quality dental restoration.
The computer modeling and milling technique essentially utilizes scanned digitized images of the area which is to be restored, and then creates a dental restoration by milling suitable materials. One computer may be associated with the scanning apparatus, another computer with the milling machine, and yet another computer may process the scanned data to produce the 3D image of the dental restoration. All of these functions could conceivably be done in the same computer, which computer can be wired to the scanning station and the milling station.
U.S. Pat. No. 5,452,219, discloses a method of mold manufacture via a computer controlled milling machine, which mold is used for the preparation of dental restorations. The patent discloses the steps of scanning a tooth model in order to obtain data of the three-dimensional surface of the model, processing the data to create a tool path program, and using the program to control the direct fabrication of a tooth mold which is the negative image of the tooth model. The mold then may be used to make an artificial tooth. However, the mold is not suitable for use when molding with high temperature ceramics.